Field of the Invention
The present invention relates to a resin composition, backing material for an ultrasonic vibrator, an ultrasonic vibrator, and an ultrasonic endoscope.
Description of Related Art
An ultrasonic endoscope has been used to observe an internal body for inspection and diagnosis. The ultrasonic endoscope includes an insertion portion inserted into the body, and an operation portion connected to the proximal end side of the insertion portion. An ultrasonic vibrator is provided at the distal end of the insertion portion.
The ultrasonic vibrator is schematically constituted by a piezoelectric element, a backing material provided on one surface of the piezoelectric element, and an acoustic matching layer and an acoustic lens which are provided on the other surface of the piezoelectric element. As described above, since the backing material is provided on one surface of the piezoelectric element, mechanical strength and the like are imparted to the ultrasonic vibrator. In addition, redundant vibration added to the ultrasonic endoscope is suppressed, and thus the acoustic characteristics of the ultrasonic endoscope change.
For example, Japanese Unexamined Patent Application, First Publication No. H11-252695 discloses a backing material formed of a rubber molded product having a specific hardness and a specific gravity, and a probe head and an ultrasonic diagnostic device which use a piezoelectric element fixed to the backing material. In the backing material of Japanese Unexamined Patent Application, First Publication No. H11-252695, mechanical strength and acoustic characteristics are improved.
An ultrasonic endoscope inserted into the body is subjected to a sterilization process under a high-temperature, high-pressure steam using an autoclave, or to a sterilization process using a chemical such as peracetic acid or gas (for example, hydrogen peroxide-based gas or ethylene oxide gas) before use.
However, since the ultrasonic endoscope is subjected to a sterilization process using the autoclave or the sterilization process using the chemical, there is a problem in that a disturbance occurs in an image obtained using the ultrasonic endoscope during inspection and diagnosis compared to that before the sterilization process. The disturbance in the image is caused by the deterioration of an organic material forming the ultrasonic vibrator due to the sterilization process.
There is a problem in that a bonded portion, which is a portion formed through bonding among the portions constituting the ultrasonic endoscope, is likely to be deteriorated when the ultrasonic endoscope is subjected to the sterilization process. For this, in order to limit the deterioration of a bonded portion of an endoscope during the sterilization process, for example, Japanese Unexamined Patent Application, First Publication No. 2004-358006 discloses a method of causing a specific filler to diffuse in a bonded layer that forms the bonded portion.
As a sterilization process for a medical device such as an endoscope, in the related art, a sterilization process using an autoclave or a sterilization process using ethylene oxide gas has been widely performed. However, in a case where an autoclave is used for a sterilization process of a medical device, there is a problem of thermal deterioration in the medical device. In a case where ethylene oxide gas is used for a sterilization process of a medical device, an effect on the human body of residual gas that remains in the medical device after the sterilization process causes a problem.
From this point of view, as the next sterilization process method, a sterilization process using hydrogen peroxide-based gas has attracted attention.